This patch fixes an issue that the following error happens on
swiotlb environment:
xhci-hcd ee000000.usb: swiotlb buffer is full (sz: 524288 bytes), total 32768 (slots), used 1338 (slots)
On the kernel v5.1, block settings of a usb-storage with SuperSpeed
were the following so that the block layer will allocate buffers
up to 64 KiB, and then the issue didn't happen.
max_segment_size = 65536
max_hw_sectors_kb = 1024
After the commit 09324d32d2a0 ("block: force an unlimited segment
size on queues with a virt boundary") is applied, the block settings
are the following. So, the block layer will allocate buffers up to
1024 KiB, and then the issue happens:
max_segment_size = 4294967295
max_hw_sectors_kb = 1024
To fix the issue, the usb-storage driver checks the maximum size of
a mapping for the device and then adjusts the max_hw_sectors_kb
if required. After this patch is applied, the block settings will
be the following, and then the issue doesn't happen.
max_segment_size = 4294967295
max_hw_sectors_kb = 256
Fixes: 09324d32d2a0 ("block: force an unlimited segment size on queues with a virt boundary")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
---
We investigated this issue on the following ML:
https://marc.info/?l=linux-block&m=156033909218970&w=2
drivers/usb/storage/scsiglue.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 59190d8..89c3640 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -28,6 +28,8 @@
* status of a command.
*/
+#include <linux/blkdev.h>
+#include <linux/dma-mapping.h>
#include <linux/module.h>
#include <linux/mutex.h>
@@ -99,6 +101,7 @@ static int slave_alloc (struct scsi_device *sdev)
static int slave_configure(struct scsi_device *sdev)
{
struct us_data *us = host_to_us(sdev->host);
+ unsigned int max_sectors = 0; /* 0 means no update required */
/*
* Many devices have trouble transferring more than 32KB at a time,
@@ -106,26 +109,34 @@ static int slave_configure(struct scsi_device *sdev)
* are limiting both to 32K (64 sectores).
*/
if (us->fflags & (US_FL_MAX_SECTORS_64 | US_FL_MAX_SECTORS_MIN)) {
- unsigned int max_sectors = 64;
+ max_sectors = 64;
if (us->fflags & US_FL_MAX_SECTORS_MIN)
max_sectors = PAGE_SIZE >> 9;
- if (queue_max_hw_sectors(sdev->request_queue) > max_sectors)
- blk_queue_max_hw_sectors(sdev->request_queue,
- max_sectors);
+ if (queue_max_hw_sectors(sdev->request_queue) <= max_sectors)
+ max_sectors = 0;
} else if (sdev->type == TYPE_TAPE) {
/*
* Tapes need much higher max_sector limits, so just
* raise it to the maximum possible (4 GB / 512) and
* let the queue segment size sort out the real limit.
*/
- blk_queue_max_hw_sectors(sdev->request_queue, 0x7FFFFF);
+ max_sectors = 0x7FFFFF;
} else if (us->pusb_dev->speed >= USB_SPEED_SUPER) {
/*
* USB3 devices will be limited to 2048 sectors. This gives us
* better throughput on most devices.
*/
- blk_queue_max_hw_sectors(sdev->request_queue, 2048);
+ max_sectors = 2048;
+ }
+
+ if (max_sectors > 0) {
+ struct device *dev = us->pusb_dev->bus->sysdev;
+ size_t max_dma_sectors = dma_max_mapping_size(dev) >>
+ SECTOR_SHIFT;
+
+ max_sectors = min_t(size_t, max_sectors, max_dma_sectors);
+ blk_queue_max_hw_sectors(sdev->request_queue, max_sectors);
}
/*
--
2.7.4
